The present invention relates to tonearm tracking mechanisms in phonograph players. More particularly, the present invention relates to mechanical devices constructed for the purpose of reproducing or playing back recorded audio material previously impressed, in the form or grooves, onto a surface of a disk. Such devices are commonly called phonograph players or turntables. Such disk is commonly called, among other similar words, a phonograph record or a vinyl disk. Even more particularly, the present invention describes a novel design of the tonearm mechanism, a component part of a phonograph player which is capable of tracking a groove in a phonographic disk in a controlled fashion, most especially in a tangential manner.
Conventional tonearm mechanisms fall generally into two categories: 1) a radial tracking mechanism wherein the path of a stylus, which is attached via several subcomponents to the end of one end of a tonearm, follows a curved path over the surface of a grooved disk. The curved path is a portion of a circle centered about a point near and outside the outer circumference of the disk; and 2) a tangential tracking mechanism wherein the path of a stylus, which is attached via several subcomponents to the end of a tonearm, follows a linear path over the surface of a grooved disk. The linear path over the surface corresponds to a radial line from the center of the disk and the mechanism that is employed to achieve the linear path is a form of linear bearing.
Known in the art is a third category of tonearm mechanism, namely one that has a tracking characteristic that achieves the groove-to-stylus relationship of a tangential tracking mechanism but is constructed from rotational bearings similar to those found in a radial tracking mechanism. In this third category of tonearm mechanisms, the stylus need not follow a single radial line coming from the center of the phonograph disk. Tangential tracking mechanisms are considered to be capable of more accurately rendering the recorded material on a disk because the motion of a playback stylus relative to a groove of a disk more accurately mimics the manner in which the original audio material was cut into a surface of a master disk. Tangential tracking mechanisms are not as common as radial tracking mechanisms because tangential tracking mechanisms tend to be more complicated, physically larger, and more costly to produce than radial tracking mechanisms. The present invention falls into this third category of tonearm mechanisms. U.S. Pat. Nos. 3,476,394; 3,813,100; 3,826,505; 4,153,256; 4,344,168; 4,346,466; and 4,580,258 disclose various tonearms of this category.